Well I guess I'm going to find out how long they'll live at 700-750hp. I'll upgrade when I have to. I'm hoping with the lightweight of this boat they'll be ok. I want to go over 120 mph with the bravos.

It's not the rpm's that kill a Bravo it's the torque. The counter rotation setup is especially susceptable to torque induced metal fatigue of the top cap. The top cap is the weakest link on a counter bravo because the torque applied to the driven gear is upward motion and eventually distorts the top cap where it will completely fail or allow water intrusion. I have seen both, and both are fatal for the drive obviously. I would suggest billet top caps, available through any of our HP sources and even though some might not agree I would swap the drives every 100 hours or so.

I'm surprised no-one else has mentioned this.....

Just 8-10psi?????? That is a little on the crazy side. 5-6#'s will make 700hp+
Call John at the Bravo Shop and discuss some Bmax's. They won't cost 50k.

Agree with Griff-- you don't need 8-10 lbs of boost.

What how many cubes/HP and was it blown or NA?...and was it a twin engine app boat or single app when your drive failed? Just curious, thanks

Kamma, here is the run down on the set up.
2002 29 Foutain Fever, single engine 575SCI with Whipple intercooler, Dart Pro1 alum heads, roller cam, 5psi boost and ECM reprogrammed. Dyno was 703HP and 738ibft torque.
Bravo 1 XR drive was rebuilt by All American Drive Service. New XR prop shaft, new XR vertical shaft. New clutch, clutch shaft and upper XR gears were cryo’ed and I sent them to have them surface treated. New lower gears also sent to cryo, REM polish and surface treated. XR upper case was upgraded to larger clutch bearings, AADS custom steel tower, Max Machine Worx billet top cap with 7/16” studs. All new bearings throughout… So basically a totally rebuilt drive with some good upgrades.
Running a stock 30 pitch Bravo 1 prop left hand.
All I can say is junk XR gear set. I never came close to getting into the throttle as I was waiting for 10 hours. Always baby it getting on plain.
I have to etch the gear that broke and see if there may be a fold from the forming process. I will also check hardness…
Lower gears looked like new and did not show any signs of wear at all. Clutch shaft bearing surfaces looked new also.
Have basically the same setup now but a standard Bravo 1 upper case with the thicker nose and the AADS mods, steel tower, billet retaining ring, Max cap… and went with XZ gears cryo’ed and also surface treated.
AADS had a full shelf of broken XR gears with one tooth broke all the way to the root same as mine. People not running the horsepower that I am are even breaking them.
Just got a 28 Bravo 1 prop to run in hopes to take a little torque off the drive.

This is all correct. Finned top caps should be the first upgrade. Next larger shafting in the lower or an xr lower would be second. XR uppers/gears are a poor choice from what I've seen.

I've ran my bravos for 200 hrs with 600hp in front of them and they are still tight. Change your drive oil every 40-50 hours , don't stab the throttles when you take off and let off when you catch air. All drives fail eventually.

im running a b1 in the back of a 496/whipple...only mods on the bravo is a max top cap and synthetic oil...im keeping my fingers crossed

the whipple setup on hp500 will put u at 730 to 750 hp.bi is good for 400 hp ,bixr is good for 600.mercury will not put xr drive behind anything above 600sc.with a light boat your bi drives and 750 hp will not live long,with xr drives,u will live a while if u dont accelerate hard,and change lube often.i recommend u put 75 hrs on xr drives,then rotate drives[left on right right on left for 75 more hrs,then replace gear sets,also,switch to max machine works clutch shafts.iv been there,done that,good luck.:party-smiley-004: